基于反射层的变层速度模型时深转换方法
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摘要
基于反射波法的地震勘探技术是在时间域中认识地下地质情况的 ,由于地震波传播速度场的变化 ,反射成像和地下地质体间并非是一个简单的镜像对称关系 ,而是一种变异的镜像结果。要正确的认识地下地质体 ,必须把时间域中的地震数据恢复到深度域中。在断裂发育的断块区或复杂的逆掩构造区 ,由于断层错动及地层褶皱等因素 ,具有不同速度特征的地层在断层处相互接触或同一套地层多次重复。在这些地方地下空间速度场在短距离内会产生很大的变化 ,速度场变得相当复杂 ,准确的时深转换成为一件非常困难的事情。文章以反射层、断层面等时间域中的地质边界为约束条件 ,以钻井资料建立基础速度结构 ,采用“基于反射层的变层速度模型结构建立时深转换速度场”方法 ,实现精确时深转换。该方法应用灵活、建场方式直观 ,非常适合于各种复杂构造的时深转换
Seismic exploration technology on the basis of reflected wave is to identify subsurface geological circumstances in time domain.Owing to the change in seismic wave propagation velocity field the relation between reflection imaging and subsurface geological body is not a simple mirror image symmetrical one,being a variable mirror image result.In order to identify correctly subsurface geological body,it is imperative to make the seismic data in time domain be restored to the ones in depth domain.In fault-developed block or in complicated overthrust structural area,the strata being of various interval velocities may be in touch with each other or the same strata appear many times at the faults because of these factors as fault offset and formation fold,etc.At these places,an accurate time-depth conversion becomes very difficult owing to the fact that the subsurface spacial velocity field may be greatly changed within a short distance,which makes the velocity field very complex.By taking the geological boundaries,i.e.reflection horizon and fault plane,etc.,in time domain as the binding conditions,the accurate time-depth conversion can be realized on the basis of setting up the foundational velocity structure through drilling data and by use of the method of "Building up time-depth conversion velocity field in view of variable interval velocity model structure of reflection horizon".Application of the method is convenient and the way of building up field is audio-visual,which is very suitable for the time-depth conversion of various complicated structures.
Seismic exploration technology on the basis of reflected wave is to identify subsurface geological circumstances in time domain.Owing to the change in seismic wave propagation velocity field the relation between reflection imaging and subsurface geological body is not a simple mirror image symmetrical one,being a variable mirror image result.In order to identify correctly subsurface geological body,it is imperative to make the seismic data in time domain be restored to the ones in depth domain.In fault-developed block or in complicated overthrust structural area,the strata being of various interval velocities may be in touch with each other or the same strata appear many times at the faults because of these factors as fault offset and formation fold,etc.At these places,an accurate time-depth conversion becomes very difficult owing to the fact that the subsurface spacial velocity field may be greatly changed within a short distance,which makes the velocity field very complex.By taking the geological boundaries,i.e.reflection horizon and fault plane,etc.,in time domain as the binding conditions,the accurate time-depth conversion can be realized on the basis of setting up the foundational velocity structure through drilling data and by use of the method of "Building up time-depth conversion velocity field in view of variable interval velocity model structure of reflection horizon".Application of the method is convenient and the way of building up field is audio-visual,which is very suitable for the time-depth conversion of various complicated structures.
引文
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